A systematic review of the value of generic preoperative investigations in elective surgical patients was carried out. A generic preoperative test was defined as an investigation recommended preoperatively for all patients of a particular type (e.g., in a certain age range or with a particular comorbidity), that was not directly indicated by either the surgical procedure or the condition for which the procedure is being carried out. The starting point for this review was to update the Health Technology Assessment (HTA) report to include additional evidence published between January 1996 and February 2002 and to identify and review all evidence (1966-2002) for additional tests covered by the guideline (i.e., pregnancy tests, lung function tests and blood gases). For a full transcript of the review, please refer to Appendix 1 of the full version of the original guideline document CD-ROM.

Search Strategy for Identification of Studies

Databases were searched from 1995 to December 2001 for tests considered in Phase A (tests in normal healthy patients, including children, varying by age and by grade of surgery [ASA grade 1] and June 2002 for tests considered in Phase B (tests of adult patients with three common comorbidities [i.e., cardiovascular disease, respiratory disease, and renal disease]). In Phase A, the search strategies deliberately included one year overlapping with the HTA review (1995) to ensure that articles were not missed because of a time lag in indexing in bibliographic databases. For tests not included in the HTA review (pregnancy testing, sickle cell tests, blood gases, and lung function tests), MEDLINE was searched from 1966 and EMBASE from 1989.

Studies were identified by the following methods:

• Electronic searching
  • The Cochrane Library 2001 issue 4 (including Cochrane Database of Systematic Reviews [CDSR], Database of Abstracts of Reviews of Effectiveness [DARE], Cochrane Controlled Trials Register [CCTR], HTA database, National Health Service [NHS] Economic Evaluations Database)
  • MEDLINE (from 1966/1995 to December 2001/June 2002)
  • EMBASE (from 1989/1995 to December 2001/June 2002
  • Science Citation Index (to December 2001/June 2002)
  • HealthSTAR (up to the end of the year 2000 when the database ceased to exist)
• Manual searching of reference lists in identified studies and reviews
• Professional contacts

The search strategies used for MEDLINE and EMBASE are detailed in the full systematic review Appendix 1, CD-ROM of the full version of the original guideline document). These search strategies were adapted for searching other databases.

Selection of Studies

Studies were identified and excluded as follows:

• Papers were excluded after reading the titles and abstract alone if they were considered definitely irrelevant.
• Full publications of the remaining articles were obtained and papers were excluded if they were irrelevant. A 10% sample of papers was reviewed by a second reviewer to ensure interobserver consistency. Disagreements were used to inform the selection and were resolved by discussion. No formal analysis of agreement was performed.
• Data were extracted from all eligible papers

Cost Effectiveness

For cost analysis, additional databases were searched (limited to the years 1995-2001):

The economic review presented in the guideline has four components:

• Estimation of unit costs of the tests under consideration
• A review of the literature around the economics of preoperative testing
• Simple economic modelling of the cost effectiveness of preoperative testing in England and Wales
• Simple economic modelling of the cost impact of preoperative testing in England and Wales

For cost analysis, in addition to the main databases searched for the main systematic review (see Chapter 3 of the full version of the original guideline document), the following additional databases were also searched (limited to the years 1995-2001):

The following guidance is based upon the best available evidence. All of the recommendations are grade D recommendations, which are based upon level IV evidence - that is, expert opinion derived from a consensus development process and the clinical experience of the Guideline Development Group.

For the tables set out by surgery grade and American Society of Anesthesiologists (ASA) grade, age categories are shown across the top of each table. For a patient with more than one comorbidity, follow the recommendations in all relevant tables.

Recommendations for individual tests are indicated as follows:

No: Test not recommended

Consider: Test to be considered (the value of carrying out a preoperative test is not known, and may depend on specific patient characteristics.)

Yes: Test recommended

Grades of Surgery

ASA grades are a simple scale describing fitness to undergo an anaesthetic. The ASA clearly states that it does not endorse any elaboration of these definitions. However, anaesthetists in the UK often qualify (or interpret) these grades as relating to functional capacity -- that is comorbidity that does not (ASA Grade 2) or that does (ASA Grade 3) limit a patient's activity (see "Characterisation of 'Mild' and 'Severe' Comorbidity, Corresponding to ASA Grades 2 and 3, for Cardiovascular, Respiratory and Renal Comorbidities" below).

ASA Grades

ASA Grade 1: "Normal healthy patient" (that is without any clinically important comorbidity and without clinically significant past/present medical history)

ASA Grade 2: "A patient with mild systemic disease"

ASA Grade 3: "A patient with severe systemic disease"

ASA Grade 4: "A patient with severe systemic disease that is a constant threat to life"

Characterisation of 'Mild' and 'Severe' Comorbidity, Corresponding to ASA Grades 2 and 3, for Cardiovascular, Respiratory and Renal Comorbidities

COAD, chronic obstructive airways disease; COPD chronic obstructive pulmonary disease; GTN, glyceryl trinitrate
Further examples are available in Appendix 2 of the full version of the guideline (see Section 5).

Grade 1 Surgery (Minor)

ASA Grade 1: Children <16 years

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 1: Adults (>16 years)

*Dipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 2: Adults with Comorbidity from Cardiovascular Disease (CVD)

ASA Grade 3: Adults with Comorbidity from CVD

ASA Grade 2: Adults with Comorbidity from Respiratory Disease

^bChest x-rays may be considered if there has been a change in patient's symptoms or if the patient needs ventilator support.

ASA Grade 3: Adults with Comorbidity from Respiratory Disease

ASA Grade 2: Adults with Comorbidity from Renal Disease

^cChest x-rays may be considered if the patient has signs of other comorbidities often associated with renal disease, such as hypertension and coronary heart failure.

^dDepending on the cause of renal disease (e.g., diabetes and hypertension)

ASA Grade 3: Adults with Comorbidity from Renal Disease

^cChest x-rays may be considered if the patient has signs of other comorbidities often associated with renal disease, such as hypertension and coronary heart failure.

Grade 2 Surgery (Intermediate)

ASA Grade 1: Children (<16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 1: Adults (>16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 2: Adults with Comorbidity from CVD

ASA Grade 3: Adults with Comorbidity from CVD

ASA Grade 2: Adults with Comorbidity from Respiratory Disease

^bChest x-rays may be considered if there has been a change in patient's symptoms, or if the patient needs ventilator support

ASA Grade 3: Adults with Comorbidity from Respiratory Disease

ASA Grade 2: Adults with Comorbidity from Renal Disease

^cChest x-rays may be considered if the patient has signs of other comorbidities often associated with renal disease, such as hypertension and coronary heart failure.

^dDepending on the cause of renal disease (e.g., diabetes and hypertension)

ASA Grade 3: Adults with Comorbidity from Renal Disease

Grade 3 Surgery (Major)

ASA Grade 1: Children (<16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 1: Adults (>16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 2: Adults with Comorbidity from CVD

ASA Grade 3: Adults with Comorbidity from CVD

ASA Grade 2: Adults with Comorbidity from Respiratory Disease

^bChest x-rays may be considered if there has been a change in patient's symptoms, or if the patient needs ventilator support

ASA Grade 3: Adults with Comorbidity from Respiratory Disease

ASA Grade 2: Adults with Comorbidity from Renal Disease

^dDepending on the cause of renal disease (e.g., diabetes and hypertension)

ASA Grade 3: Adults with Comorbidity from Renal Disease

Grade 4 Surgery (Major +)

ASA Grade 1: Children (<16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 1: Adults (>16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 2: Adults with Comorbidity from CVD

ASA Grade 3: Adults with Comorbidity from CVD

ASA Grade 2: Adults with Comorbidity from Respiratory Disease

^bChest x-rays may be considered if there has been a change in patient's symptoms, or if the patient needs ventilator support

ASA Grade 3: Adults with Comorbidity from Respiratory Disease

ASA Grade 2: Adults with Comorbidity from Renal Disease

^dDepending on the cause of renal disease (e.g., diabetes and hypertension)

ASA Grade 3: Adults with Comorbidity from Renal Disease

Neurosurgery

ASA Grade 1: Children <16 years

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 1: Adults >16 years

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

Cardiovascular Surgery

ASA Grade 1: Children (<16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

ASA Grade 1: Adults (>16 years)

^aDipstick urine testing in asymptomatic individuals is not recommended (UK National Screening Committee)

Tests for the Sickle Cell Gene in Adults and Children

The following recommendations and observations are in addition to those shown in the table above:

• The sickle cell gene is found in many nationalities including families that come from Africa, the Caribbean, the Eastern Mediterranean, Middle East and Asia. It has also been detected in Cypriot people and a few other white ethnic groups.
• It is important to offer to test all people considered to be at risk before an anaesthetic, both at hospital and dental clinics. This is especially important for patients who have a family history of ethnic groups considered to be at risk, who have a family history of homozygous sickle cell anaemia or sickle cell trait and who do not have a surgical history where it may have been detected previously.
• People of ethnic origin considered to be at risk should be offered screening, with genetic counselling before and after screening.
• Appropriate counselling for this test is important so that patients are able to give their informed consent, as there may be implications for patients who discover they are carriers of the sickle cell gene. The results of testing, even when negative, should be reported to families, with the patient's consent, and documented in the patient's medical record to avoid unnecessary repeat testing.

Pregnancy Test

The following recommendations and observations are in addition to those shown in the table above:

• The need to test for pregnancy depends on the risk presented to the fetus by the anaesthetic and surgery. All women of childbearing age should be asked sensitively whether or not there is any chance that they may be pregnant.
• Women must be made aware of the risks of surgery to the fetus.
• A pregnancy test should be carried out with the woman's consent if there is any doubt about whether the woman may be pregnant.
• Before having a chest x-ray, all women of childbearing age should be asked sensitively whether they may be pregnant

Good Practice Recommendations

During the development of this guideline, the Guideline development Group (GDG) agreed certain principles of good practice. Although the aspects of preoperative testing to which they relate were not strictly within the scope of the guideline, it is important to describe them because the guideline was developed with the assumption that these principles were in place.

Ensuring Clinical Competence

It is important to ensure that staff undertaking clinical preoperative assessments receive appropriate education and training to allow them to apply the guideline correctly.

Preoperative Assessment

It is crucial to ensure that a thorough medical history is taken from the patient to inform the recommendations about which preoperative tests to carry out. Taking a thorough medical history requires someone with the appropriate training.

Timing and Setting of Tests

The consensus process did not cover the issue of who should carry out the preoperative tests. However, it is clear that preoperative tests are often ordered or carried out by nurses in preoperative assessment clinics. The timing of tests should be appropriate for the tests concerned. It may be appropriate both from the doctor's and patient's perspective to test for certain conditions at the earliest stage possible, after a patient has been placed on the waiting list for an operation, so that there is time for the patient to be treated and for their condition to stabilise, ensuring patients are in the best possible state when they have surgery.

Some tests could be carried out in the primary care setting by the patient's General Practitioner (GP) or practice nurse. For example, when a patient is listed for a particular operation it may be appropriate for the consultant in charge of the patient's care to consider the possible tests that may be required for the patient and, after discussion with the patient, to inform their GP. Excellent communication between primary and secondary care, to ensure that test results are shared, would be essential if such changes in the responsibility and timing of testing were to be implemented.

Whoever carries out the tests, protocols for testing should be followed. This is particularly important for tests like urine analysis (dipstick), where not following the recommended protocol may render the result of the test meaningless.

Patient Information and Consent

Staff undertaking clinical preoperative assessments should discuss with patients which tests are recommended (or required), what they involve, and why they are being carried out.

Decisions about whether or not to test should follow discussion between the patient and the doctor or nurse, especially where there is uncertainty about whether a test should be recommended or not. For some tests, a positive result carries a far greater significance for the patient than others, such as testing for previously undetected diabetes, the sickle cell gene, and pregnancy.

Patients should have access to information about the tests and the possible implications of a positive result so that they can give their informed consent. Doctors or nurses carrying out or ordering tests should write in the patient's notes that they have discussed the recommended tests and their implications with the patient.

Patients should be informed of the results of tests and about the implications for treatment, and any longer term implications for their health, if the results are abnormal.

General

National Health Service (NHS) organisations should review their existing practice for preoperative testing against this guideline. The review should consider the resources required to implement fully the recommendations set out in Section 1 of the short version of original guideline document (and in the "Major Recommendations" section of this summary),the people and processes involved, and the timeline over which full implementation is envisaged. Clearly, it is in the interests of patients that the implementation timeline is as rapid as possible.

Relevant local clinical guidelines, care pathways, and protocols should be reviewed in the light of this guidance and revised accordingly.

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